textproduct: Albany

WHAT HAS CHANGED

No significant changes to the forecast.

KEY MESSAGES

1) Dry conditions with seasonably warm temperatures and low humidity levels persist through the weekend.

2) Increasing confidence for periods of rain showers and a chance of thunderstorms Mon through the middle of the week across eastern NY and western New England.

DISCUSSION

As of 245 AM EDT...

KEY MESSAGE 1...

Zonal flow aloft and sfc high pressure centered in eastern Quebec will continue our stretch of beautiful weather today across eastern NY and western New England. Expect plenty of sunshine mixed diurnally driven cumulus, comfortable humidity, and temperatures warming into the low to mid 80s in the valley with mid to upper 70s in the higher terrain. Skies clear this evening allowing temperatures to cool but overnight temperatures likely will not be quite as cool as previous nights given increasing clouds tracking west to east into the region. Coolest temperatures should occur in western New England where skies will stay clear longest supporting radiational cooling and overnight lows falling comfortably into the low to mid 50s. High pressure starts to move further to our east tomorrow into the Canadian Maritimes with broad troughing from the Great Lakes building into the Northeast. Weak subsidence from high pressure to our northeast looks to maintain enough subsidence to keep most areas dry except the southwest Adirondacks and northern and eastern Catskills where broad troughing and weak height falls along with additional lift from the terrain can support isolated to scattered showers or thunderstorms. However, given very low shear and low instability, severe weather is not expected. Our western areas are only outlined in SPC's general thunder.

KEY MESSAGE 2...

Cloud coverage and humidity increases heading into Monday as broad troughing remains overhead and wind aloft becoming west- southwesterly. While height falls are minimal, temperatures aloft cool supporting mid-level lapse rates around 5.5 - 6C/km which when combined with breaks of sun and dew points rising into the 60s will likely contribute to increased sfc based instability reaching 500 - 1000 J/kg. Very weak flow aloft once again will keep shear negligible so as isolated to scattered diurnally driven showers/storms develop, they will likely be slow moving and quickly dissipate. Higher terrain areas including the southwest Adirondacks and eastern Catskills are most favored for any isolated to scattered shower/storm. SPC maintain just general thunder across eastern NY and western New England.

There is increasing confidence that we will enter into a more unsettled period Tuesday into Wednesday with widespread likely and even categorical POPs both days across eastern NY and western New England. This is attributed to a stronger shortwave rounding the top of the expansive ridge positioned across the Central and Western CONUS and amplifying as it digs into the Great Lakes and Northeast. While there is medium to high confidence that the middle of the week will include showers and thunderstorms, there remains uncertainty on the timing and amplitude of this shortwave which will be important as we diagnosis which hazards will be at play. There are two main scenarios with the first suggesting the shortwave closes off over the Great Lakes or Ohio Valley, supporting strong southerly flow ahead of it that advects a strong plume of Gulf moisture into the Northeast Tues into Wed. This would increase the chances for heavy downpours from thunderstorms and potential for heavy rain to repeatedly impact a given area increasing the chance for isolated instances of flooding. The second solution suggests a delay in the shortwave amplifying until it is further east. Increased upper level divergence ahead of it interacts with a stalled boundary that has been impacting the Carolinas/mid-Atlantic for the past few days resulting in a coastal low developing and tracking to southern New England. We would likely be positioned within the cool conveyor belt north of the boundary and sfc low leading to more widespread stratiform rain. The latest NBM still shows 30 to 60% chance for at least 1" of rain across eastern NY and western New England between 8PM Tues and 8PM Wed with a 15 to 35% for over 2 inches. As was mentioned in the previous discussion, dry antecedent conditions heading into this event keep flooding concerns low as high flash flood guidance values indicate soils should be able to handle 1 to 2 inches of rain falling over multiple hours. If the first scenario ends up occurring, flooding concerns will likely increase as this favors convection potentially repeatedly impacting a given area. Latest WPC Excessive Rainfall Outlook shows widespread Marginal Risk both Tues and Wed suggesting isolated instances for flash flooding potential. This product will update again tonight.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

Through 18z/Sun...VFR conditions are expected to continue through much of the upcoming TAF period. Fair weather cumulus this afternoon will dissipate tonight with just some high clouds passing overhead later tonight through Sunday morning. Despite the high clouds, some patchy fog may still form at KGFL/KPSF between 06-12z/Sun where vsby reductions to IFR/LIFR will be possible. Wind will generally be 5 kt or less through the period.

Outlook...

Sunday Night: No Operational Impact. NO SIG WX. Monday: Moderate Operational Impact. Chance of SHRA...TSRA. Monday Night: Moderate Operational Impact. Chance of SHRA...TSRA. Tuesday: High Operational Impact. Definite SHRA...TSRA. Tuesday Night: High Operational Impact. Definite SHRA...TSRA. Wednesday: High Operational Impact. Definite SHRA...TSRA. Wednesday Night: High Operational Impact. Likely SHRA...TSRA. Thursday: Moderate Operational Impact. Likely SHRA...TSRA..

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...None. MA...None. VT...None.